Over the last few weeks I have noticed a minor weepage of engine oil from somewhere on the distributor. This got a bit more noticeable on a fast (yes honestly), 120 mile journey today. It's the two-part, original 500 distributor and the gasket seal to the engine block is definitely not the culprit. I wondered if there should be a gasket where the top half joins to the base; at the swivel-point.
Is there a seal or "O"-ring anywhere on it? I can't remember there being one.
Alternatively, it might be connected with my recent change to synthetic oil as I read that it is more "searching" and will find gasket weaknesses.
I think there are some tiny holes in the base of the distributor body which would presumably be to allow any excess oil vapour to get out. Could it be an excess of excess vapour?

I can't find a seal. There is a groove under the top half which might accept an "O"ring. If so, this is also missing from my spare distributor. So I've used the old Permatex sealant and we'll see if it's any better tomorrow.

Hi Peter;
just had a good look at my (factory) parts book and (again, factory) work-shop manual--no sign of an '0' ring in either book.